Maintenance procedures for some types of aircraft require that the exhaust nozzle remain in the aircraft while the engine is being exchanged. The primary reason for this requirement is to save maintenance time when it becomes necessary to replace or perform maintenance on the engines.
The engine is formed with an annular flange which abuts an annular flange formed on the exhaust nozzle. In the prior art, a plurality of spaced bores are formed around the circumference of each flange. The engine is mounted to the exhaust nozzle by aligning the bores of the two flanges and then inserting bolts therebetween which are secured by nuts. The bolts circumferentially align the engine with the exhaust nozzle and provide a lightweight, reliable connection. Additionally, the bolts carry tension and shear loads applied to the joint to prevent axial separation of the engine flange from the exhaust nozzle flange.
Although a bolted flange connection between the engine and exhaust nozzle is advantageous in some respects, it substantially increases the maintenance time required to exchange an engine or exhaust nozzle. One problem with bolted connections involves initially positioning the engine flange in proper alignment with the exhaust nozzle flange. Such flanges have planar abutting surfaces and it is difficult and time consuming to align the flanges vertically and circumferentially when the engine is being lifted into place against the exhaust nozzle.
Additionally, while the bolts and nuts in the bottom half of the engine flange and exhaust nozzle flange are easily accessible by removing the cowling around the lower half of the engine, the bolts and nuts in the top half of the flanges are extremely difficult or impossible to reach with the engine and exhaust nozzle mounted in the aircraft. This is because there is usually a limited amount of space at that location, and the available space is filled with other hardware and/or structure.
Attempts have been made in the prior art to solve this problem such as by providing access doors in the aircraft so that the bolts and nuts at the top of the engine and exhaust nozzle flanges can be reached. The problem with this solution is that access doors increase the weight of the aircraft, add expense to its construction and do not fully alleviate the access problem.